Final answer:
The minimum thickness of a transformer vault floor depends on the load it needs to support, with smaller transformers requiring a minimum thickness of 8 inches and larger transformers needing up to 20 inches.
Step-by-step explanation:
The minimum thickness of a transformer vault floor for it to meet up with bricks or cement filled blocks depends on the load it will need to support. Generally, a transformer vault floor needs to be designed to handle the weight of the transformers and other equipment placed on it. In most cases, a minimum thickness of 8 inches would be sufficient for smaller transformers, while larger transformers may require a thickness of up to 20 inches.